Molding unit for containers, equipped with a boxing device with improved compactness

ABSTRACT

Disclosed is a molding unit for the forming of a container provided with a hollow recess toward the interior of the container, including: a mold provided with a lateral wall defining a cavity having the impression of at least one portion of the container, provided with a housing formed hollow in a protrusion forming a projection toward the interior of the cavity and opening into the cavity; and a boxing device having an insert mounted in translation relative to the lateral wall between a retracted position in which the insert is retracted in the housing, and a deployed position in which the insert projects outside of the housing, a projection whose transverse extension is less than or equal to 85% of the cumulative transverse extension of the protrusion and of the insert.

This invention relates to the forming of containers, particularlybottles, jars, as well as canisters, from blanks of thermoplasticmaterial (such as polyethylene terephthalate or PET), and morespecifically to the forming of containers provided with hollow recessessuch as incorporated handles.

Let us recall that the manufacture of containers generally comprises ablow-molding operation that takes place in a mold whose wall defines acavity within which the blank is introduced, the latter, during blowmolding, conforming to the wall under the effect of the high gaspressure that prevails in the blank, previously heated so as to enableits plastic deformation.

Some containers can be provided with hollow recesses toward the interiorof the container and made with an esthetic purpose (for example,creating curves) or with a functional purpose (making a handle forgrasping the container).

To achieve this, a molding unit is generally used that is provided witha movable insert that is initially retracted in the wall of the mold andthat is deployed in the presence of the container being formed in themold to push the material back when it reaches the wall, as illustratedin the international application WO 2010/063900 (Sidel Participations).

The technique described in this document, designed for a linear-typemold (which comprises two half-molds mounted in translation in relationto one another), is not easily replicable in wallet-type molds (in whichthe half-molds are mounted in rotation in relation to one another),because of the considerable space required, particularly radial, for theboxing device controlling the movement of the insert.

One objective is to propose a molding unit for containers provided witha hollow recess, which offers an improved compactness.

For this purpose, a molding unit is proposed for the forming of acontainer provided with a hollow recess toward the interior of thecontainer, this molding unit comprising:

-   -   a mold provided with a lateral wall defining a cavity having the        impression of at least one portion of the container and that        extends along a main axis defining a vertical direction, this        lateral wall being provided with a housing that opens into the        cavity;    -   a boxing device comprising:        -   an insert mounted in translation relative to the lateral            wall along a transverse axis between a retracted position in            which the insert is at least partially retracted in the            housing, and a deployed position in which the insert            projects at least partially into the cavity outside of the            housing,        -   an actuator that is integral with the insert and provided            with a piston; this molding unit being characterized in            that:    -   the housing is formed hollow in a protrusion forming a        projection toward the interior of the cavity,    -   in deployed position, the insert forms, beyond the protrusion, a        projection whose transverse extension, denoted E, is less than        or equal to 85% of the cumulative transverse extension, denoted        F, of the protrusion and of the insert:

E≦0.85·F

Since the recess is partially formed by a stationary part of the mold(the protrusion), it is possible to limit the travel of the insert,promoting the radial space required of the mold.

Various additional characteristics can be provided, alone or incombination. Thus, for example:

-   -   the travel, denoted H, of the insert, measured between its        retracted position and its deployed position, is less than or        equal to 20 mm:

H≦20 mm

-   -   the transverse extension E of the projection formed by the        insert beyond the protrusion is greater than or equal to 30% of        the cumulative transverse extension F of the protrusion and of        the insert:

E≧0.3·F

-   -   the chord length, denoted B, measured in a horizontal plane        containing the transverse axis, of the projection formed by the        insert in deployed position, is less than or equal to 80% of the        cumulative chord length, denoted A, of the protrusion and of the        projection formed by the insert in deployed position:

B≦0.8·A

-   -   the chord length, denoted B, measured in a horizontal plane        containing the transverse axis, of the projection formed by the        insert in deployed position, is greater than or equal to 35% of        the cumulative chord length A of the protrusion and of the        projection formed by the insert in deployed position:

B≧0.35·A

-   -   the insert has a width C, measured horizontally, whose relation        to the chord length B is less than or equal to 2.3:

B≦2.3·C

-   -   the insert has a width C, measured horizontally, whose relation        to the chord length B is greater than or equal to 1.3:

B≧1.3·C

-   -   the relation between the chord length B of the projection formed        by the insert in deployed position and its transverse extension        E is less than or equal to 3.5:

B≦3.5·E

-   -   the relation between the chord length B of the projection formed        by the insert in deployed position and its transverse extension        E is greater than or equal to 2.2:

B≧2.2·E

-   -   the chord length B of the projection formed by the insert in        deployed position is less than or equal to 75 mm:

B≦75 mm

-   -   the chord length B of the projection formed by the insert in        deployed position is greater than or equal to 50 mm:

B≧50 mm

-   -   the relation between the cumulative chord length, denoted A,        measured in a horizontal plane containing the transverse axis,        of the protrusion and of the projection formed by the insert in        deployed position and the cumulative transverse extension,        denoted F, of the protrusion and of the insert in deployed        position is less than or equal to 3.3:

A≦3.3·F

-   -   the relation between the cumulative chord length, denoted A,        measured in a horizontal plane containing the transverse axis,        of the protrusion and of the projection formed by the insert in        deployed position and the cumulative transverse extension,        denoted F, of the protrusion and of the insert in deployed        position is greater than or equal to 2:

A≧2·F

-   -   the transverse extension E of the projection formed by the        insert beyond the protrusion is less than or equal to 35 mm:

E≦35 mm

-   -   the transverse extension E of the projection formed by the        insert beyond the protrusion is greater than or equal to 10 mm:

E≧10 mm

-   -   taking into account an offset, denoted I, between the main axis        and the transverse axis, the transverse extension E is such        that:

E≦45 mm−I

Other objects and advantages of the invention will be brought out in thedescription of an embodiment, made below with reference to theaccompanying drawings in which:

FIG. 1 is a cutaway view in perspective showing a molding unit providedwith a pair of boxing devices;

FIG. 2 is an exploded cutaway view in perspective showing, from theinside, a half-mold and its associated boxing device;

FIG. 3 is an exploded cutaway view in perspective showing, from theoutside, a half-mold and its associated boxing device;

FIG. 4 is a view in perspective and in broken section showing thehalf-mold of FIG. 2 and FIG. 3;

FIG. 5 is a horizontal cutaway view showing the molding unit, taken inthe area of the boxing devices;

FIG. 6 is a vertical detail cutaway view showing a boxing device inretracted position of the insert, during the forming of a container;

FIG. 7 is a view similar to FIG. 6, showing the insert in deployedposition;

FIG. 8 is a horizontal detail cutaway view showing the boxing device inretracted position of the insert, during the forming of a container;

FIG. 9 is a view similar to FIG. 8, showing the insert in deployedposition;

FIG. 10 is an exploded view in perspective showing a portion of themolding unit;

FIG. 11 is a horizontal detail cutaway view illustrating the scaling ofthe mold and the insert;

FIG. 12 is a vertical partial cutaway view of the mold, showing the twofacing inserts in deployed position;

FIG. 13 is a view in perspective of a container formed in a molding unitas illustrated in the preceding figures;

FIG. 14 is a horizontal cutaway view of the container of FIG. 13, alongthe cutting plane XIV-XIV;

FIG. 15 is an exploded cutaway view in perspective showing, from theinside, a half-mold and its associated boxing device, according to avariant embodiment;

FIG. 16 is a horizontal detail cutaway view showing the boxing device ofFIG. 15 in deployed position of the insert;

FIG. 17 is a view in perspective, from the front, of an insert thatequips the half-mold of FIG. 15 and FIG. 16;

FIG. 18 is a view in perspective, from the back, of the insert of FIG.17.

In FIG. 1, shown in section and in perspective, there is a molding unit1 for forming, from a blank (typically a preform), a container 2 (suchas a bottle or a canister, as illustrated in FIG. 13) provided with ahollow recess 3 formed toward the interior of the container 2. Thecontainer 2 is provided, in a standard way, with a body 4, a bottom anda neck 2A that opens opposite the bottom. In the example illustrated inFIG. 13 and FIG. 14, the hollow recess 3 is a handle formed in the body4 of the container to make it easy to grasp.

In this case, the body 4 is, in the area of the handle, subdivided intoa front part 4A and a back part 4B. As illustrated in FIG. 14, the frontpart 4A and the part 4B have rounded shapes. The back part 4B is thepart that is intended to be held in the user's palm when the user grabsthe container individually.

The molding unit 1 comprises, firstly, a mold 5 provided with a lateralwall 6 that defines a cavity 7 having the impression of a portion of thecontainer 2. In this particular case, the cavity 7 has the impression ofthe body 4 of the container 2, the mold 5 further comprising a bottom 8having the impression of the bottom of the container 2. The mold 5 ismade of metal, for example steel or aluminum (this term also coveringthe alloys of aluminum). The cavity 7 (and therefore the container 2)extends along a main axis X that defines a vertical direction. Any planeperpendicular to the main axis X is called horizontal.

According to an embodiment illustrated in the drawings, the lateral wall6 comprises two half-molds 5A, 5B each defining a half-impression 7A, 7Bof the body 4 of the container 2 and that are mounted in rotationrelative to one another around a common axis formed by a hinge, between:

-   -   an open position, in which the half-molds 5A, 5B are angularly        separated from one another to make possible the insertion of the        blank and the removal of the formed container 2,    -   a closed position (illustrated in FIG. 1 and in FIG. 5), in        which the half-molds 5A, 5B are applied against one another and        enclose between them the bottom 8 of the mold, thus to form the        cavity 7 and define the impression of the container 2 to be        formed.

The lateral wall 6 is provided with a housing 9 that opens into thecavity 7. As is seen particularly in FIG. 6 and in FIG. 7, this housing9 is made hollow in a protrusion 10 that forms a projection toward theinterior of the cavity 7 and that forms a portion of thecounter-impression of the hollow recess 3 that defines the handle.

According to an embodiment illustrated particularly in FIG. 1 and inFIG. 5, corresponding to a container 2 provided with two hollow recesses3, preferably symmetric in relation to a general central plane ofsymmetry of the container 2 and together forming the handle, eachhalf-mold 5A, 5B is provided with a housing 9 that opens into thehalf-impression 7A, 7B and is made hollow in a protrusion 10 that formsa projection toward the interior of the cavity 7.

The molding unit 1 comprises secondly, and for each housing 9, a boxingdevice 11. The term “boxing” designates a technique for local shaping ofthe material by pushing back by means of a movable part, carried outduring the forming of the container 2 (and more specifically initiatedduring the pre-blow-molding and blow-molding phases of the container 2).

Each boxing device 11 comprises an insert 12, with a complementary shapeof a housing 9 and accommodated in it. Each insert 12 has a frontsurface 13 having the impression of a local portion (i.e., of relativesmall surface area) of the container 2, and more specifically of thebottom of the hollow recess 3. The front surface 13 is intended to pushback the material of the container 2 to complete the impression of thehollow recess 3, as will be explained below. The insert 12 isadvantageously made of aluminum.

As is seen in FIG. 1 and in FIG. 5, the molding unit 1 is equipped witha pair of boxing devices 11 (preferably symmetric) whose inserts 12 areplaced opposite one another.

Each insert 12 is mounted in translation relative to the lateral wall 6(i.e., in the example illustrated, relative to each half-mold 5A, 5B)along a transverse axis T between a retracted position (FIG. 6 and FIG.8) in which the insert 12 is at least partially retracted into thehousing 9, and a deployed position (FIG. 7 and FIG. 9) in which theinsert 12 projects at least partially into the cavity 7 outside of thehousing 9.

More specifically, and as is clearly visible in FIG. 6 and in FIG. 8, inretracted position of the insert 12, the front surface 13 is included inthe housing 9 and does not go beyond the protrusion 10, whereas indeployed position of the insert 12, the front surface 13 projects intothe cavity 7 and extends into the extension of the protrusion 10 tocomplete with it the impression of the recess 3 formed hollow in thecontainer 2.

This configuration is not exclusive. Thus, according to anotherembodiment, in retracted position of the insert 12, the front surface 13of the insert 12 is situated projecting in relation to the internal edgeof the protrusion 10. According to still another embodiment, inretracted position of the insert 12, the front surface 13 of the insert12 is found in the extension of the internal edge of the protrusion 10.

As is seen clearly in FIG. 2 and FIG. 3, the insert 12 (like its housing9) has an asymmetric rotational profile around the axis T, which blocksthe rotation of the insert 12 around it. More specifically, the insert12, preferably, has a height (along the general axis X of the mold 5)that is greater than the width (in a horizontal plane). In the exampleillustrated, the insert 12 has an oval profile with a long,approximately vertical axis.

As illustrated in the drawings, each boxing device 11 further comprisesan added sleeve 14, mounted in a hollowed-out complementary recess 15 inthe lateral wall 6 (i.e., in the example illustrated, in each half-mold5A, 5B) and attached to it. The sleeve 14 is advantageously made ofsteel.

Each boxing device 11 further comprises an actuator 16 that is integralwith the insert 12 to move it from its retracted position to itsdeployed position, and vice-versa, and comprising for this purpose apiston 17 mounted in translation in the sleeve 14. The actuator 16 ispreferably made of aluminum.

According to an embodiment illustrated in the drawings, and moreparticularly visible in FIG. 6 to FIG. 9, the sleeve 14 comprises a backwall 18 that, when the sleeve 14 is inserted into its recess 15, isflush with an outer surface 19 of the mold 5, and a cylinder 20 thatprojects transversely from the back wall 18 and ends by an edge 21.

The sleeve 14 defines on the inside a chamber 22 in which the piston 17is mounted. Like the insert 12, the sleeve 14 and the recess 15accommodating it, just like the piston 17, have an asymmetric rotationalprofile around the transverse axis T, which blocks any rotation of thepiston 17 around it, promoting the precision of guiding in translationof the insert 12. More specifically, the sleeve 14, its recess 15 andthe piston 17, preferably, have a height (along the general axis X ofthe mold 5) that is greater than their width (in a horizontal plane). Inthe example illustrated, the sleeve 14, the recess 15 and the piston 17have an oval profile with a long, approximately vertical axis.

The piston 17 subdivides the chamber 22 into a rear half-chamber 22A anda front half-chamber 22B. In the example illustrated, the rearhalf-chamber 22A is restricted on the inside by the piston 17 and on theoutside by the back wall 18 of the sleeve 14. Also in the exampleillustrated, the front half-chamber 22B is restricted on the outside bythe piston 17 and on the inside by the bottom of the recess 15.

The sleeve 14 is provided, on an external peripheral surface of thecylinder 20, with a rear groove 23 that opens into the rear half-chamber22A by several openings (here in the form of through holes) 24 in thesleeve 14, arranged on its periphery. In the example illustrated, thesleeve 14 is provided with two diametrically opposed openings 24,arranged in this particular case along a vertical axis. As a variant,the sleeve 14 could include a higher number of openings 24, for examplefour openings 24 arranged at 90° (or otherwise) around the transverseaxis T.

The sleeve 14 is further provided, on the external peripheral surface ofthe cylinder 20, with a front groove 25 that opens into the fronthalf-chamber 22B by several notches 26 made in the edge 21 and arrangedon the periphery of the sleeve 14. In the example illustrated, thesleeve 14 is provided with six notches arranged at about 60° around thetransverse axis T.

Rings 27 mounted on the external surface of the cylinder 20, andcompressed between it and the recess 15, ensure the fluidtightness ofthe grooves 23, 25 in relation to one another, and therefore of thehalf-chambers 22A, 22B in relation to one another.

After its introduction into the recess 15, the sleeve 14 is attached tothe lateral wall 6 of the mold 5. As can be seen in the drawings, andmore particularly in FIG. 2 and FIG. 3, the sleeve 14 is attached to thelateral wall 6 by means of at least one bracket 28 comprising a body 29attached to the mold 5 by means of screws 30, and a tongue 31 projectingfrom the body 29 and resting, on the outside, against the back wall 18of the sleeve 14. In the example illustrated, the sleeve 14 is attachedto the lateral wall 6 by means of a pair of brackets 28 mountedvertically on both sides of the sleeve 14.

To avoid any protrusion on the outer surface 19 of the mold 5, eachbracket 28 advantageously is housed in a hollow recess 32 made in acomplementary way in the lateral wall 6 of the mold 5, while the tongue31 is housed in a recess 33 made in the back wall 18 of the sleeve 14.

According to an embodiment illustrated in the drawings, the actuator 16comprises a rod 34 that extends radially projecting from the piston, andonto which the insert 12 is fastened, for example by screwing.

More specifically, in the example illustrated, the insert 12 is fastenedonto the rod 34 by means of a screw 35 that goes through the piston 17and the rod 34 and that engages helically with a threaded hole 36 madein a rear surface 37 of the insert 12, opposite the front surface 13.

The insert 12 is advantageously locked in rotation relative to theactuator 16 by means of a pin 38 mounted in a hole 39 made in the rod 34and one projecting end of which is housed in a hole 40 made, opposite,in the rear surface 37 of the insert 12.

As can clearly be seen in FIG. 6 to FIG. 9, the piston 17 is providedwith an added peripheral segment 41, in contact with the cylinder 20 andthat, in addition to the rings 27, ensures the fluidtight partitioningof the two half-chambers 22A, 22B. The segment 41 is advantageously madeof a material having a low coefficient of friction, for example ofbronze or, preferably, of polytetrafluoroethylene (PTFE).

As is seen also in FIG. 6 to FIG. 9, the recess 15 ends, on the side ofthe cavity 7, by a partition 42 that separates the recess 15 from thehousing 9 and delimits the front half-chamber 22B on the inside.

This partition 42 is pierced with a hole 43 in which the rod 34 of theactuator 16 is mounted in translation, with the interposition of one ormore sealing rings 44A that isolate the front half-chamber 22B from thehousing 9, and preferably also with interposition of one or more guiderings 44B. In the example illustrated, the ring 44A is a dynamic lipring. As for the ring 44B, it can be made of PTFE(polytetrafluoroethylene).

Each boxing device 11 comprises a fluid circuit 45 for controlling themovement of the piston 17, at least from its retracted position to itsdeployed position. According to an advantageous embodiment, the fluidcircuit 45 is pneumatic, the fluid used being a gas (typically air)under pressure.

Each circuit 45, for this purpose, comprises at least one primary fluidduct 46 for supplying the chamber 22 (and more specifically the rearhalf-chamber 22A) that communicates with the chamber 22 (and morespecifically with the rear half-chamber 22A) by the openings 24.

In practice, and as can be seen particularly in FIG. 1 to FIG. 3, FIG.6, FIG. 7 and FIG. 10, the primary duct 46 is drilled in the mold 5 andopens, by an upstream end 47, onto an upper surface 48 of the mold 5and, by a downstream end 49, into the recess 15 in line with the reargroove 23 (FIG. 6 and FIG. 7).

According to an embodiment illustrated in the drawings, controlling themovement of the piston 17 is of the dual action type, each fluid circuit45 being configured to control, furthermore, the movement of thecorresponding piston 17 from its deployed position to its retractedposition.

For this purpose, each circuit 45 comprises a secondary fluid duct 50for supplying the front half-chamber 22B, which communicates with it bythe notches 26.

More specifically, and as can be seen particularly in FIG. 4, thesecondary duct 50 is drilled in the mold 5 and opens, by an upstream end51, on the upper surface 48 of the mold 5 and, by a downstream end 52,into the recess 15 in line with the front groove 25.

According to an embodiment illustrated in the drawings, the primary duct46 is made approximately vertically in the lateral wall 6 of the mold 5,whereas the secondary duct 50 is made obliquely (however, with a rathersmall angle) in the lateral wall 6 of the mold 5. In FIG. 10, theprimary duct 46 and the secondary duct 50 are represented in bold brokenlines.

As is seen in FIG. 1 and FIG. 10, the molding unit 1 comprises apneumatic connector 53 for supplying pressurized fluid at least from theprimary duct 46. For this purpose, the connector 53 comprises a primaryinlet 54 in communication with the upstream end 47 of the primary duct46. This primary inlet 54 advantageously appears in the form of a ductdrilled in the connector 53, and which opens into a primary plug 55(here of the male type) for connecting to a primary tube (not shown) forsupplying pressurized fluid.

The primary inlet 54 is, via the primary plug 55 and the primary tube,preferably connected to a fluid source, typically gas, at high pressure,advantageously greater than 20 bars (and, for example, about 40 bars).It can be the source used for the blow molding of the containers or elseanother pressure source, generating, if necessary, a pressure with avalue that is different from the blow-molding source.

In the example illustrated, where controlling the movement of the piston17 is dual action, and where, apart from the primary duct 46, thepneumatic circuit 45 comprises a secondary passage 50 for supplying thefront half-chamber 22B, the pneumatic connector 53 comprises a secondaryinlet 56 in communication with the upstream end 51 of the secondary duct50. This secondary inlet 56 advantageously appears in the form of a ductdrilled in the connector 53, and which opens into a secondary plug 57(here also of the male type) for connecting to a secondary tube (notshown) for supplying pressurized fluid.

The secondary inlet 56 is, via the secondary plug 57 and the secondarytube, connected to a fluid source having comparatively lower pressure,advantageously less than or equal to 12 bars (and, for example, about 7bars).

The upstream ends 47, 51 of the ducts 46, 50 advantageously come outnear one another, so as to enable their common connection to therespective sources of pressurized fluid via a single connector 53mounted on the upper surface 48 of the mold 5, as illustrated in FIG. 1.

The connector 53 is attached to the mold 5 by snapping-on or, as in theexample illustrated in FIG. 1 and in FIG. 10, by means of at least onescrew 58.

According to an advantageous embodiment illustrated in FIG. 1 and inFIG. 10, the molding unit 1 comprises a cover 59 mounted on the uppersurface 48 of the mold 5 and interposed between it and the connector 53.

As can be seen in FIG. 10, the molding unit 1 comprises a fluid circuit60 (for example, hydraulic) for thermal regulation of the wall 6. Thefluid used is advantageously a liquid, for example water or oil. Thiscircuit 60 is provided to maintain the temperature of the wall 6 at anapproximately constant temperature, either low (typically on the orderof 10° C.) to ensure a cooling of the container 2 only just formed, orhigh (typically on the order of 120° C.) to ensure a heat-setting of thecontainer 2 and thus to enhance, by thermal means, its crystallinity(and therefore its mechanical strength).

As is seen in FIG. 10, the fluid circuit 60 includes passages 61 drilledin the wall 6 of the mold 5 and extends between a supply opening 62 andan evacuation opening 63 made in the upper surface 48 of the mold 5. Inother words, the fluid circuit 60 comes out, by the supply opening 62and by the evacuation opening 63, on the upper surface 48 of the mold 5.

For reasons of ease of production (by drilling), the passages 61 aresubdivided into several sections, most notably:

-   -   an upstream section 61A, which comes out on the supply opening        62 and includes several holes made vertically, horizontally        and/or obliquely in the wall 6;    -   a downstream section 61B, which comes out on the evacuation        opening 63 and also includes several holes made vertically,        horizontally and/or obliquely in the wall 6 and which        communicates with the upstream section 61A in a middle zone of        the mold 5.

As can be seen in FIG. 10 where they are visible transparently in dashedlines, the passages 61 are drilled so as to go around the recess 15 andso as not to intersect the ducts 46, 50 of the pneumatic fluid circuit45.

As is seen in FIG. 1 and in FIG. 10, the molding unit 1 comprises afluid connector 64 mounted on the upper surface 48 of the mold 5 toensure the supply to the fluid circuit 60 of fresh (or, respectively,reheated) liquid and to ensure the evacuation from it of the reheated(or cooled) liquid, after it has performed a heat exchange with the wall6.

For this purpose, the fluid connector 64 comprises a fluid inlet 65(here in the form of a duct drilled in the connector 64) incommunication with the supply opening 62, and a fluid outlet 66 (herealso in the form of a duct drilled in the connector 64) in communicationwith the evacuation opening 63.

In the example illustrated in FIG. 10, the openings 62, 63 are at adistance from one another, and come out on the upper surface 48 in anapproximately diametrically opposite way. To make possible asimultaneous fluid connection of the openings 62, 63 via a compactconnector 64, the mold 5 comprises a groove 67 that is made in the uppersurface 48, which extends from an outer end 68 located in line with theevacuation opening 63 to an inner end 69 located in the vicinity of thesupply opening 62.

According to a preferred embodiment, illustrated in FIG. 1 and in FIG.10, where the molding unit 1 is provided with an added cover 59 attachedto the upper surface 48 of the mold 5, this cover 59 is interposedbetween the upper surface 48 and the fluid connector 64.

As can be seen by transparency in FIG. 10, the cover 59 is provided withthrough holes 70 to 73 for putting each connector 53, 64 incommunication with its respective circuit 45, 60.

In a more detailed manner, the cover 59 comprises:

-   -   a first through hole 70 (oblique) for putting the primary inlet        54 of the pneumatic connector 53 in communication with the        upstream end 47 of the primary duct 46;    -   a second through hole 71 (vertical) for putting the secondary        inlet 56 of the pneumatic connector 53 in communication with the        upstream end 51 of the secondary duct 50;    -   a third through hole 72 (vertical) for putting the fluid inlet        65 in communication with the supply opening 62;    -   a fourth through hole 73 (vertical) for putting the fluid outlet        66 in communication with the evacuation opening 63. In the        example illustrated, the fourth through hole 73 opens in line        with the inner end 69 of the groove 67, by which the fourth        through hole 73 is in fluid communication with the evacuation        opening 63.

The gas and liquid (typically air and water) fluidtightness of theinterface between the cover 59 and the upper surface 48 is ensured,around the upstream ends 47, 51 of the ducts 46, 50 and around theopenings 62, 63 (and more specifically around the groove 67), by meansof elastomer rings 74, for example of silicone or of natural orsynthetic rubber.

The attaching of the cover 59 onto the upper surface 48 of the mold 5can be, in the example illustrated, ensured by means of screws 75.

The fact that the pneumatic circuit 45 and the fluid circuit 60 bothcome out on the upper surface 48 of the mold 5 makes it possible tooffset on it the connections for supplying the circuits 45, 60, andthereby offers at least three advantages:

-   -   first, it is not necessary to accommodate lateral accesses to        the intake (and evacuation) tubes, which simplifies the        structure of the molding unit 1, and in particular parts        supporting the mold 5;    -   then, the radial bulk of the molding unit 1 is reduced;    -   finally, the connections through the upper surface 48 are        simpler and easier for any technician responsible for the        maintenance of the molding unit 1.

Furthermore, to ensure the precise positioning of the insert 12 relativeto the cavity 7, and to limit in addition the wear of the actuator 16and of the mold 5, each boxing device 11 advantageously comprises a pairof Silentblocs 76, 77, fastened onto the actuator 16 on both sides ofthe piston 17, namely:

-   -   a rear Silentbloc 76 fastened onto the piston 17 by means of        screws 78, and which, in retracted position of the insert 12, is        sandwiched between the piston 17 and the back wall 18 (FIG. 6,        FIG. 8);    -   a front Silentbloc 77 press-fitted on the rod 34 and fastened        onto the piston 17 by means of screws 78 and which, in deployed        position of the insert 12, is sandwiched between the piston 17        and the partition 42 (FIG. 7, FIG. 9).

It should be noted here that the term “Silentbloc” (in the singular) isa French trademark of the company HUTCHINSON S.A., from which a commonname was originated that is used to designate (see the LarousseDictionary [dictionnaire Larousse], for example) a flexible mountingdevice or a device for shock absorbing between two elements: the use ofthe terms “silentbloc” or “silentblocs” in this application refers tosuch a device.

According to a preferred embodiment, each Silentbloc 76, 77 is made ofpolyurethane, preferably in a grade of polyurethane marketed by theTrelleborg Company under the name Zurcon Z20®. This material exhibitsthe dual advantage of an enhanced hardness (promoting the positioningprecision of the insert 12) and of a good resistance to wear, whichpromotes the reliability and durability of the boxing device 11.

The mounting of each boxing device 11 in each half-mold 5A, 5B isillustrated in FIG. 2 and FIG. 3.

The Silentblocs 76, 77 are fastened onto the actuator 16 by means ofscrews 78; the pin 38 is press-fitted into the hole 39 and the screw 35for fastening the insert 12 introduced into the actuator 16 to cause theend of the rod 34 to project. The piston 17 is then inserted into thesleeve 14, then the sleeve, equipped with its sealing rings 27, isintroduced, from the outside of the mold 5, into its recess 15 along thetransverse axis T, the rod 34 being inserted into the hole 43.

The sleeve 14 is attached to the lateral wall 6 of the mold by means ofbrackets 28, which are mounted in their respective recesses 32 andscrewed onto the lateral wall 6. The insert 12 is mounted from theinterior of the half-mold 5A, 5B while being introduced into the housing9 along the transverse axis T until contact is made with the end of therod 34, the pin 38 being housed in the hole 40 made in the rear surface37 of the insert 12.

The fastening of the insert 12 onto the rod 34 is then performed bymeans of the screw 35, whose tightening in the threaded hole 36 isensured by means of a screwdriver or an appropriate wrench (depending onthe impression formed in the screw head) that goes through an opening 79made, along the axis T, in the back wall 18 of the sleeve 14.

Once the fastening of the insert 12 to the actuator 16 is done, theopening 79 is closed in a fluidtight manner by means of a plug 80press-fitted or screwed into it, as illustrated in FIG. 6 to FIG. 9.

Illustrated in FIG. 11, FIG. 12 and FIG. 14 is the scaling of the partsof the molding unit 1 that makes it possible to form the hollow recess 3in the container 2.

In this framework, the following are noted:

-   A the cumulative chord length, measured in a horizontal plane    containing the transverse axis T, of the protrusion 10 and of the    projection formed by the insert 12 in deployed position;-   B the chord length, also measured in a horizontal plane containing    the transverse axis T, of the projection formed by the insert 12 in    deployed position beyond the protrusion 10;-   C the width, measured horizontally (i.e., perpendicular to the main    axis X), of the insert 12;-   D the chord length, measured in a horizontal plane containing the    axis T, of the protrusion 10, in retracted position of the insert    12;-   E the maximum transverse extension (measured along the axis T) of    the projection formed by the insert 12 beyond the protrusion 10;-   F the maximum cumulative transverse extension (measured along the    axis T) of the protrusion 10 and of the projection formed beyond the    protrusion 10 by the insert 12 in deployed position;-   F′ the maximum transverse extension (measured along the axis T) of    the protrusion 10 alone;-   G the width, measured transversely, of the rear portion 4B of the    body 4 (the width G is considered equally on the container 2 or on    its impression in the mold 5);-   H the travel of the insert 12 (or of the piston 17), measured in mm    between the retracted position (in dashed lines in FIG. 11) and the    deployed position (in solid lines in FIG. 11);-   I on the container 2, the offset, measured in a horizontal plane,    between the axis X (considered in the container 2) and the bottom of    the hollow recess 3: in the mold 5, I corresponds approximately to    the offset, measured in a horizontal plane, between the axis X    (considered in the mold 5) and the transverse axis T.

The extensions E, F and F′ are called “maximum” to demonstrate the case,as it is illustrated in FIG. 11, where the recess 3, and the protrusion10 and the insert 12 do not exhibit symmetry in relation to a verticalplane containing the transverse axis T. This is why the extensions E andF are measured from the side of the insert 12 (or from the side of theprotrusion 10) maximizing their value, as FIG. 11 illustrates it.

As has already been seen, the protrusion 10 forms a portion of thecounter-impression of the hollow recess 3 in the container 2. Inretracted position of the insert 12, the transverse extension F′ of theprotrusion 10 alone is such that between the facing protrusions 10, agap persists whose width, measured transversely and denoted K, issufficient to make possible, during the blow molding, the passing,during its expansion, of the preform from which the container 2 isformed. This width K is typically on the order of 40 mm.

This makes it possible to limit the travel H of the insert 12 andtherefore the radial bulk of the boxing device 11, promoting thecompactness of the molding unit 1.

In practice, the travel H of the insert 12 from its retracted positionto its deployed position is small, i.e., it is less than or equal to 20mm. Furthermore, this travel is advantageously greater than or equal to10 mm. The travel H of the insert 12 is typically on the order of 15 mm.

The cumulative transverse extension F of the protrusion 10 and of theinsert 12 in deployed position is such that, in deployed position of thetwo inserts 12, a gap persists between them, so that each hollow recess3 is recessed. In other words, the handle formed in the container 2 bythe two hollow recesses 3 back to back does not pass through, asillustrated in FIG. 14. The width, measured transversely, of the gapbetween the facing inserts 12 in deployed position is denoted J. Thiswidth J is typically on the order of 15 mm, which corresponds to thedistance between the two hollow recesses 3 that together form the handleof the container 2.

The extensions E and F are such that E is less than or equal to 85% ofF:

E≦0.85·F

Although limited, the projection formed beyond the protrusion 10 by theinsert 12 in deployed position makes it possible to deepen the recess 3despite a small travel H.

Furthermore, the recess 3 must be deep enough to facilitate the graspingof the container 2. For this purpose, the transverse extension E isadvantageously greater than or equal to 30% of the cumulative transverseextension F:

E≧0.3·F

More specifically, the transverse extension E is preferably less than orequal to 35 mm:

E≦35 mm

On the other hand, this transverse extension E is preferably greaterthan or equal to 10 mm:

E≧10 mm

In addition, the transverse extension E is preferably less than or equalto 45 mm from which is subtracted the value of the offset I:

E≦45 mm−I

Likewise, it is advantageous to limit the chord length B of theprojection formed by the insert 12 in deployed position as a function ofthe cumulative chord length A of the protrusion 10 and of the projectionformed by the insert 12.

Thus, B is preferably less than or equal to 80% of A:

B≦0.8·A

In this way, the amount of material that undergoes the stretching due tothe boxing remains limited in vertical extension (along the axis X).

Furthermore, B is preferably greater than or equal to 35% of A:

B≧0.35·A

This makes it possible, in spite of everything, to stretch the materialenough without, however, stretching it to the point of adverselyaffecting the visual appearance of it (the phenomenon of overstretchingresults in a whitish discoloration of the material).

It is also possible to scale the insert 12 by linking its chord length Bto its width C.

Thus, the relation between the chord length B and the width C isadvantageously less than or equal to 2.3:

B≦2.3·C

On the other hand, this relation is advantageously greater than or equalto 1.3:

B≧1.3·C

It is also possible to scale the insert 12 by linking its chord length Bto its transverse extension E.

Thus, the relation between the chord length B of the projection formedby the insert 12 in deployed position and its transverse extension E ispreferably less than or equal to 3.5:

B≦3.5·E

In contrast, this relation is advantageously greater than or equal to2.2:

B≧2.2·E

More specifically, the chord length B of the projection formed by theinsert 12 in deployed position is preferably less than or equal to 75mm:

B≦75 mm

In contrast, the chord length B of the projection formed by the insert12 in deployed position is preferably greater than or equal to 50 mm:

B≧50 mm

It can be advantageous to connect the cumulative chord length A to thecumulative transverse extension F.

More specifically, the relation between the cumulative chord length A tothe cumulative transverse extension F is preferably less than or equalto 3.3:

A≦3.3·F

In contrast, this relation is advantageously greater than or equal to 2:

A≧2·F

In the table below, examples of ranges of values (in millimeters) arelisted for the parameters A to J:

Minimum Value Maximum Value Parameter (Example) (Example) A 80 120 B 5075 C 25 40 D 60 100 E 10 35 F 30 50 G 45 70 H 10 20 I 0 45 J 14 25

To form a container 2, the procedure is as follows.

The first step is to introduce into the mold 5, in its open position, ablank previously heated to a temperature greater than the glasstransition temperature of its material (typically, a blank of PET, whoseglass transition temperature is on the order of 80° C., is heated to atemperature of about 120° C.). Each insert 12 is then in its retractedposition.

The mold 5 is then closed, and a fluid (particularly air) under pressure(for example from about 7 to 15 bars) is injected into the blank, whichis, preferably, simultaneously stretched by means of a sliding rod.Under the pressure, the material of the blank is brought to the vicinityof the lateral wall 6 and of the mold bottom 8, without, however, beingapplied there in a firm manner. As illustrated in FIG. 6 and FIG. 8, itis possible that, under the pressure, the material expands slightly intothe housing 9 while possibly partially being applied partially againstthe front surface 13 of the insert 12.

Each insert 12 is then moved toward its deployed position. For thispurpose, a pressurized fluid (here, air at a high pressure, greater thanor equal to 20 bars and typically on the order of 40 bars) is injected,via the primary duct 46 and the rear groove 23, into the rearhalf-chamber 22A, whereas the fluid present in the front half-chamber22B is simultaneously evacuated, via the front groove 25, through thesecondary duct 50. Under the pressure difference between the rearhalf-chamber 22A and the front half-chamber 22B, the piston 17 is, withthe insert 12 with which it is integral, moved transversely in thedirection of the cavity 7, until striking, by means of the frontSilentbloc 77, against the partition 42, which thus determines the endof travel of the insert 12 in deployed position.

The insert 12 pushes the material back like a plunger (without, however,puncturing it) until reaching its deployed position, the handle thenbeing formed hollow in the body 4 of the container 2 (FIG. 7 and FIG.9).

At the same time as the insert 12 is moved toward its deployed position,the pressure in the container 2 is increased (typically up to a value ofbetween about 20 and 40 bars) to improve the impression-taking of thecontainer 2 against the lateral wall 6 and the mold bottom 8. Since thelateral wall 6 and the mold bottom 8 are thermally regulated, theholding of a close contact of the material against them promotes thecooling (or, in the case of a heat-setting, the heating) of thecontainer 2, promoting its mechanical rigidity.

After a time lag (of several tenths of a second), the container isdepressurized, the mold 5 is opened, and the container 2 is removed fromthe mold 5.

The insert 12 is placed back in its retracted position before or afterthe opening of the mold 5. For this purpose, the pressurized fluid isinjected, via the secondary duct 50 and the front groove 25, into thefront half-chamber 22B, whereas the fluid present in the rearhalf-chamber 22A is simultaneously evacuated, via the rear groove 23, bythe primary duct 46. Under the pressure difference between the fronthalf-chamber 22B and the rear half-chamber 22A, the piston 17 is, withthe insert 12 with which it is integral, moved transversely toward theexterior of the mold 6, until striking, by means of the rear Silentbloc76, against the back wall 18 that determines the end of travel of theinsert 12 in retracted position.

By comparison with an ordinary boxing device in which the piston 17would be directly mounted in a recess made in the mold 5, the presenceof the added sleeve 14, which serves as a wearing part, limits (eveneliminates) the wear of the lateral wall 6 of the mold 5, promoting thereliability of the molding unit 1.

Furthermore, the incorporation of the fluid circuit 45 in the mold 5,and more specifically the making of the supply ducts 46, 50 in thelateral wall 6 of the mold 5, with connections made on its upper surface48, limits the transverse bulk of the mold 5, promoting the generalcompactness of the molding unit 1.

The separation of the recess 15 from the housing 9 by the partition 42and the mounting of the insert 12 from the inside of the half-mold 5A(or 5B) make it possible to achieve a good fluidtightness of thehalf-chambers 22A, 22B promoting the effectiveness of the boxing device11, and therefore improving the quality of the container 2.

The asymmetric shape (here, oval) of the insert 12 and of the sleeve 14prevents the rotation of the insert 12, promoting a goodimpression-taking of the hollow recess 3. The preferential uniformdistribution of the openings 24 (and of the notches 26) makes itpossible to ensure a good distribution of the pressure in the rearhalf-chamber 22A (or in the front half-chamber 22B), promoting theguiding precision of the insert 12 and a good impression-taking of thehollow recess 3.

A variant embodiment of the molding unit 1 has been represented in FIG.15 to FIG. 18.

This variant contains all of the characteristics of the molding unit 1described above, with the exception of the following additional ormodified characteristics.

Firstly, the insert 12 is provided with at least one passage 81 thatextends from a rear end 82, by which it opens into the housing 9, to afront end 83 by which it opens onto the front surface 13.

According to a first embodiment, the (or each) passage 81 can be drilledin the periphery of the insert 12, in tunnel (or groove) form. Accordingto a preferred embodiment illustrated in FIG. 15 to FIG. 18, the (oreach) passage 81 is drilled in the body of the insert 12.

In this case, and as can clearly be seen in FIG. 18, the (or each)passage 81 opens onto the rear surface 37 of the insert 12.

According to an embodiment illustrated in FIG. 17 and FIG. 18, theinsert comprises a plurality of passages 81. These passages 81 areadvantageously distributed around the rod 34 when it is fastened ontothe insert 12. In the example illustrated, where the insert 12 isprovided with a counterbore 84, in which the rod 34 is fitted, it isseen that the passages 81 are distributed around this counterbore 84.

Secondly, the front half-chamber 22B is in fluid communication with thehousing 9.

For this purpose, the rod 34 is grooved, i.e., it is provided withgrooves 85 made in its outer surface parallel to its axis (parallel tothe axis T).

These grooves 85 facilitate the fluid communication between the fronthalf-chamber 22B and the housing 9.

These arrangements make it possible to achieve, via the fronthalf-chamber 22B, the grooves 85, the housing 9 and the passage (orpassages) 81, a circulation of fluid (i.e., air if the fluid used isair) that:

-   -   facilitates the cooling (or the thermal regulation) of the        insert 12,    -   facilitates the cooling of the material of the container 2 as        well as its separation from the front surface 13 of the insert        12 when it is withdrawn.

This fluid circulation is achieved during the injection of fluid intothe front half-chamber 22B controlling the retraction movement of thepiston 17 (and therefore of the insert 12): a portion of the injectedfluid leaks into the housing 9 via the grooves 85 and is introduced intothe passage (the passages) 81 by the rear end 82 to come out on thefront surface 13 by the front end 83, as illustrated by the arrows inthe detail inset of FIG. 16.

By limiting the heating of the insert 12, at the same time as thelateral wall 6 of the mold 5 is cooled, there is avoided, on the onehand, the rise in the temperature of the insert above the glasstransition temperature (Tg) of the constituent thermoplastic material ofthe container and, on the other hand, an expansion of the insert 12 thatwould hinder its proper sliding into the housing 9. The sheet of aircreated between the front surface 13 of the insert 12 and the container2 makes it possible to maintain the shape of the hollow recess 3 formedin the container 2 by the insert 12 in its deployed position.

More specifically, the injection of fluid at low pressure into the fronthalf-chamber 22B (and therefore into the housing 9) is achieved beforethe injection of fluid at high pressure into the rear half-chamber 22Ais stopped. The fluid circulation on the front surface 13 of the insert12 therefore begins before its retraction. Consequently, the aircirculates between the blow-molded container 2 and the insert 12 andensures a cooling thereof.

The pressure in the container 2 is then released, and then the pressurein the rear half-chamber 22A is also released. Since the pressure in thefront half-chamber 22B is maintained, the insert 12 is moved from itsdeployed position toward its retracted position and then the pressure inthe front half-chamber 22B is released.

This structural design, and the operating method that has just beendescribed, makes it possible to simplify the structure of the mold sincethe pressurization ducts of the front half-chamber 22B are used toensure the cooling of the insert 12, which prevents resorting todedicated arrangements (for example, a specific duct for supplyingcoolant). Furthermore, since the container 2 is used to create a walleffect for guiding the air flows that are distributed in sheets lickingthe front surface 13, this leads to a good effectiveness of the cooling.Accordingly, the temperature of the insert 12 can be kept constantlybelow the glass transition temperature of the material of the container2.

1. Molding unit (1) for the forming of a container (2) provided with ahollow recess (3) toward the interior of the container (2), this moldingunit (1) comprising: a mold (5) provided with a lateral wall (6)defining a cavity (7) having the impression of at least one portion ofthe container (2) and that extends along a main axis (X) defining avertical direction, this lateral wall (6) being provided with a housing(9) that opens into the cavity (7); a boxing device (11) comprising: aninsert (12) mounted in translation relative to the lateral wall (6)along a transverse axis (T) between a retracted position in which theinsert (12) is at least partially retracted in the housing (9), and adeployed position in which the insert (12) projects at least partiallyinto the cavity (7) outside of the housing (9), an actuator (16) that isintegral with the insert (12) and provided with a piston (17); wherein:the housing (9) is formed hollow in a protrusion (10) forming aprojection toward the interior of the cavity (7), in deployed position,the insert (12) forms, beyond the protrusion (10), a projection whosetransverse extension, denoted E, is less than or equal to 85% of thecumulative transverse extension, denoted F, of the protrusion (10) andof the insert (12):E≦0.85·F
 2. Molding unit (1) according to claim 1, wherein the travel,denoted H, of the insert (12), measured between its retracted positionand its deployed position, is less than or equal to 20 mm:H≦20 mm
 3. Molding unit (1) according to claim 1, wherein the transverseextension E of the projection formed by the insert (12) beyond theprotrusion (10) is greater than or equal to 30% of the cumulativetransverse extension F of the protrusion (10) and of the insert (12):E≧0.3·F
 4. Molding unit (1) according to claim 1, wherein the chordlength, denoted B, measured in a horizontal plane containing thetransverse axis (T), of the projection formed by the insert (12) indeployed position is less than or equal to 80% of the cumulative chordlength, denoted A, of the protrusion (10) and of the projection formedby the insert (12) in deployed position:B≦0.8·A
 5. Molding unit (1) according to claim 1, wherein the chordlength, denoted B, measured in a horizontal plane containing thetransverse axis (T), of the projection formed by the insert (12) indeployed position is greater than or equal to 35% of the cumulativechord length A of the protrusion (10) and of the projection formed bythe insert (12) in deployed position:B≧0.35·A
 6. Molding unit (1) according to claim 4, wherein the insert(12) has a width C, measured horizontally, whose relation to the chordlength B is less than or equal to 2.3:B≦2.3·C
 7. Molding unit (1) according to claim 4, wherein the insert(12) has a width C, measured horizontally, whose relation to the chordlength B is greater than or equal to 1.3:B≧1.3·C
 8. Molding unit (1) according to claim 4, wherein the relationbetween the chord length B of the projection formed by the insert (12)in deployed position and its transverse extension E is less than orequal to 3.5:B≦3.5·E
 9. Molding unit (1) according to claim 4, wherein the relationbetween the chord length B of the projection formed by the insert (12)in deployed position and its transverse extension E is greater than orequal to 2.2:B≧2.2·E
 10. Molding unit (1) according to claim 4, wherein the chordlength B of the projection formed by the insert (12) in deployedposition is less than or equal to 75 mm:B≦75 mm
 11. Molding unit (1) according to claim 4, wherein the chordlength B of the projection formed by the insert (12) in deployedposition is greater than or equal to 50 mm:B≧50 mm
 12. Molding unit (1) according to claim 1, wherein the relationbetween the cumulative chord length, denoted A, measured in a horizontalplane containing the transverse axis (T), of the protrusion (10) and ofthe projection formed by the insert (12) in deployed position and thecumulative transverse extension, denoted F, of the protrusion (10) andof the insert (12) in deployed position is less than or equal to 3.3:A≦3.3·F
 13. Molding unit (1) according to claim 1, wherein the relationbetween the cumulative chord length, denoted A, measured in a horizontalplane containing the transverse axis (T), of the protrusion (10) and ofthe projection formed by the insert (12) in deployed position and thecumulative transverse extension, denoted F, of the protrusion (10) andof the insert (12) in deployed position is greater than or equal to 2:A≧2·F
 14. Molding unit (1) according to claim 1, wherein the transverseextension E of the projection formed by the insert (12) beyond theprotrusion (10) is less than or equal to 35 mm:E≦35 mm
 15. Molding unit (1) according to claim 1, wherein thetransverse extension E of the projection formed by the insert (12)beyond the protrusion (10) is greater than or equal to 10 mm:E≧10 mm
 16. Molding unit (1) according to claim 1, wherein, taking intoaccount an offset, denoted I, between the main axis (X) and thetransverse axis (T), the transverse extension E is such that:E≦45 mm−I
 17. Molding unit (1) according to claim 2, wherein thetransverse extension E of the projection formed by the insert (12)beyond the protrusion (10) is greater than or equal to 30% of thecumulative transverse extension F of the protrusion (10) and of theinsert (12):E≧0.3·F
 18. Molding unit (1) according to claim 2, wherein the chordlength, denoted B, measured in a horizontal plane containing thetransverse axis (T), of the projection formed by the insert (12) indeployed position is less than or equal to 80% of the cumulative chordlength, denoted A, of the protrusion (10) and of the projection formedby the insert (12) in deployed position:B≦0.8·A
 19. Molding unit (1) according to claim 3, wherein the chordlength, denoted B, measured in a horizontal plane containing thetransverse axis (T), of the projection formed by the insert (12) indeployed position is less than or equal to 80% of the cumulative chordlength, denoted A, of the protrusion (10) and of the projection formedby the insert (12) in deployed position:B≦0.8·A
 20. Molding unit (1) according to claim 2, wherein the chordlength, denoted B, measured in a horizontal plane containing thetransverse axis (T), of the projection formed by the insert (12) indeployed position is greater than or equal to 35% of the cumulativechord length A of the protrusion (10) and of the projection formed bythe insert (12) in deployed position:B≧0.35·A